Chaostoolkit-lib

Changed

* Switched from pycodestyle/pylama to `black`, `flake8`, `isort`
* Update CI builds to build, lint, and test
* Allow nesting of secrets
* Secrets loaded from a vault can be overridden by variables
* In secrets testcases, change the os.environ to be a patch, not an assignment within the testcase.
* Add `.github/workflows/close_stale_issues.yaml` to mark issues as `Stale`
after 365 days of inactivity and to close them after 7 days of being marked
`Stale`.
* Run `pyupgrade --py36-plus` across whole project
* Updated `.github/workflows/release.yaml` to check that both `CHANGELOG.md`
and `chaoslib/__init__.py` get updated in line with a new version
* Updated `Makefile` to specify `python3` instead of `python`

Added

* Added `.github/workflows/check_pr.yaml` which checks if a PR has modified the
CHANGELOG.md and if it changed/added tests

* Added dry run options:
* `--dry=activities` runs all activities as dry run. (same as the old flag)
* `--dry=actions` runs all actions as dry run.
* `--dry=probes` runs all probes as dry run.
* `--dry=pause` runs all activities with no pausing.

Changed

- In `run.py`, changed method names containing `continous` to `continuous`

- In `run.py`, changed variable `continous_hypo_event` to `continuous_hypo_event`

- In `run.py`, changed `Strategy.CONTINOUS` to `Strategy.CONTINUOUS`

- In `types.py`, changed `Strategy.CONTINOUS` to `Strategy.CONTINUOUS`
**(BREAKING COMPATABILITY)**

- In `types.py`, changed expected `value` from `continously` to
`continuously`

- In `types.py`, changed expected paramater from `continous_hypothesis_frequency`
to `continuous_hypothesis_frequency`

- In `test_run.py`, changed method names containing `continous` to `continuous`
and method names containing `immediatly` to `immediately`

- In `test_run.py`, changed parameter `continous_hypothesis_frequency` to
`continuous_hypothesis_frequency` and variable strategy from `Strategy.CONTINOUS`
to `Strategy.CONTINUOUS`

- In `test_run.py`, changed method names containing `continous` to `continuous`

- In `run_handlers.py`, changed method names containing `continous` to `continuous`

- Changed other minor typos

Added

- Added a new control function, called `validate_control` that takes a
control declaration and allows the control implementation to validate itself.
This is useful when you want to ensure your control is well-formed before
starting to run the experiment. The control validates itself. It's an
optional control hook, like others. See [7][7] for context.

[7]: https://github.com/chaostoolkit/chaostoolkit-addons/issues/7

Changed

- Fix activity name in the logs shown when the Python provider links to an
unknown function [223][223]

[223]: https://github.com/chaostoolkit/chaostoolkit-lib/issues/223

Removed
- Remove the problematic log line from exit.py

While using the safeguards addon, when some safeguard probe fails, sometimes it doesn't stop the experiment and instead continues to run. In some cases it gets completely stuck.

Problem is that the chaostoolkit uses Signals in order to interrupt threads. Sometimes the interrupt exception gets caught by that logger and it just swallows it.
Therefore the experiment continues to run. [210][ctk210]

[ctk210]: https://github.com/chaostoolkit/chaostoolkit/issues/210

Changed

- Library now requires Python 3.6 [208][ctk208]

[ctk208]: https://github.com/chaostoolkit/chaostoolkit/issues/208

Changed

- Fix typo in `setup.cfg` from `install_require` to `install_requires`

Changed

- Fix release workflow by updating to latest setuptools